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1.

You have the set of numbers {-6,-2,-7,10,2,8,7,-6,-3,2}. What is the ratio of positive numbers to negative numbers?

2.

Benjamin had two out of four of the 12 items required to start the school year. What fraction of the number of items was he lacking?

Completa.

3.

There is always a 1 to 1 correspondence between the number guanines (G) and the number of cytosines (C) in a DNA molecule. The same is true of the relationship between adenine (A) and thymine (T). Of course professor Floop knows this. He analyzed a strand of DNA and determined the amounts of C and G it contained. If the molecule was20% G, what was the percentage of A?

4.

Dylan analyzed some pollen grains found near a site that is thought to have been inhabited by humans many thousands of years ago. He found70examples of grass pollen,20examples of oak pollen, and20examples of unknown kinds of pollen. Let's assume his analysis was typical of the site and that another scientist could study the site and determine the exact same proportions of the three classes of pollen. Assuming this, if there were21,500pollen grains in the area of study, how many of them would be of an unknown type?

Key #2

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5.

Soils around the world vary in their organic matter content. Organic matter comes from living things or things that used to be alive. For example, in comparing a soil from Nebraska to one from Arizona, it would not be unusual for the Nebraska soil to have a greater amount of organic matter by a factor of5to2. If you had two such samples and the sample from Arizona contained7g of organic matter, how many grams of organic matter would there be in Nebraska soil of equal mass? Round your answer to the nearest hundredth.

6.

The lava output from the volcano in crater park has quadrupled over the past30days. If the lava output30days ago was2tons of rock per week, what is the output now?

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7.

Kevin calculated the mass of a toy car to be25.7grams. Hunter calculated the mass of the same car but made an error and obtained a mass that was greater than Kevin's by a ratio of5to2. What was Hunter's calculation for the mass of the car?

8.

A sealed steel container of methane gas is slowly heated. The temperature increases by5C every20minutes. If the initial temperature was25C, what will the initial to final temperature ratio (Ti/Tf) be after two hours?

Completa.

9.

A sample of steel made at the Bigtown Steel Works, was analyzed and found to contain0.03% carbon (by mass). How many kilograms of this kind of steel could be made from1.3kg of carbon? Round your answer to the nearest hundredth if needed.

10.

Morgan worked overtime at the lab to perform a chemical analysis on some sludge of unknown composition. She found it to be26.2% water by mass. If she completely dried a119-g (original mass) of the sludge, how much water was removed in the drying process? Round your answer to the nearest hundredth.

Key #2

Completa.

11.

In the local coed softball league, the male to female ratio is8:4. If there are166players in the league, how many are female?

12.

The Littleville basketball team tries2field goals for every free throw. They makemetàof their attempts of either try. If they make11free throws in a game, how many field goals are they expected to make?